Trigonella foenum-graceum commonly known as fenugreek is an herbaceous plant of the leguminous family and is native to Western Asia, from where it has spread widely over Europe, the Mediterranean and rest of Asia. It is one of the oldest cultivated plants and through ages has found wide applications as a food, a food additive and as a traditional medicine in every region wherein it has been cultivated. The leaves and both the ripe and unripe seeds of Trigonella foenum-graceum are used as vegetables. The seeds also function as a food preservative and are added to pickles, chutneys and other similar food products. The ripe seeds have numerous applications in the traditional medicine system of India. Fenugreek has been used in treating colic flatulence, dysentery, diarrhea, dyspepsia with loss of appetite, chronic cough, dropsy, enlargement of liver and spleen, rickets, gout and diabetes.
The fenugreek seed contains a central hard yellow embryo surrounded by a corneous and comparatively large layer of white, semi-transparent endosperm. The endosperm is surrounded by a tenacious, dark brown testa. The endosperm and testa are referred to as husk. In mature seeds the majority of the endosperm cells are nonliving, the cytoplasmic content of which are occluded by the store reserves viz galactomannan. Fenugreek seed contains a large number of compounds such as volatile oil, fixed oils, proteins, carbohydrates, dietary fibers, hemicellulose, galactomannans, cellulose, saponins, resins, pigments, vitamins, minerals and others.
Typical analysis results of fenugreek seeds are documented in the table 1 hereunder:
TABLE 1Typical analysis of fenugreek seedsCONSTITUENTPERCENTAGE1.MOISTURE9.02.ASH3.23.LIPIDS7.04.PROTEINS26.05.STARCH1.66.FIBER48.0Mucilage20.0Hemicelluloses17.3Cellulose8.2Lignin2.57.SAPONIN4.88.TRIGONELLINE0.37(Source: THE WEALTH OF INDIA, CSIR GOVT. OF INDIA PUBLICATION.)
Various seed components of Trigonella foenum-graceum along with the dietary fibers have an important role in the treatment and management of several disorders such as obesity, coronary heart disease, diabetes, piles, fissures, chronic constipation and diverticulitis. The saponins are reported to contain active components that are anti-carcinogenic, anti-microbial and/or anti-oxidant. The dietary fiber is the non-absorbable and indigestible fibrous portion, which is not assimilated by the body and is non-caloric and has substantially no nutrition value. It includes both soluble and insoluble fibers. Insoluble dietary fibers primarily comprise cellulose, lignin and some hemicelluloses; while soluble dietary fiber comprises pectin, gums and some hemicelluloses.
Owing to the versatile functionality of the various seed components of Fenugreek, attempts have been made to isolate these components using various processes. These processes mainly make use of organic solvents and/or specialized equipments for extraction of the components. Majority of these attempts emphasize upon isolation of fractions that include primarily soluble dietary fibers with high protein content.
U.S. Pat. No. 5,997,877 discloses a process for the fractionation of fenugreek seeds to provide various fractions thereof including a soluble dietary fiber fraction, de-flavored fenugreek seed, high protein fenugreek meal, dioscin and other saponins, along with fenugreek oleoresins. The process disclosed herein comprises tempering the fenugreek seed to moisture content in the range of 14% to 22%; flaking or milling the fenugreek seed; followed by solvent extraction and precipitation of the soluble gum. In one aspect the flaked fenugreek seeds are treated with polar alcohols at high temperatures to isolate oleoresin component prior to isolation of soluble dietary fiber; this process may however lead to loss of some amount of dietary fibers. Further, the soluble dietary fibers are isolated by heating the milled fenugreek over-fraction comprising endosperm and hull with water as a solvent at 60° C. for 4 hours which may affect the quality of the final product as well as the viscosity of the dietary fiber obtained. U.S. Pat. No. 6,495,175 discloses a method employing two different solvent extraction stages for obtaining substantially pure fixed oil, oleoresin and dietary fiber from Fenugreek seeds wherein the first extraction isolates fixed oils and the second extraction isolates oleoresin to finally provide dietary fibers that remain after extraction. Described herein is a special extraction system for better efficiency. Further the process disclosed in this application utilizes grinding and sieving of the fenugreek seeds for imparting higher surface area for better extraction which is well-known in the art. Use of high temperature, solvents and specialized extractor during the extraction process, makes the process very difficult on the commercial scale. Additionally, since the embryo is not separated from the dietary fiber at the time of grinding or isolation, the fibers obtained have higher protein content, which is not a desirable attribute for a pharmaceutical excipient.
U.S. Pat. No. 5,658,571 discloses a process for preparing debitterised powder of the fenugreek seed. Guar gum and bran are discussed to be blended with the debitterised powder of the seed of fenugreek to prepare formulations that can be used as fiber supplements. The process for debitterization of fenugreek seed disclosed involves the use of solvents and special jacketed extractor and therefore tends to have similar disadvantages as discussed above. The debitterised powder comprises a total dietary fiber of 48% by weight wherein the insoluble fiber is 28% by weight and the soluble fiber is 20% by weight. Further since the embryo is not separated from the dietary fiber during the preparation process, the debitterised powder is likely to have higher protein content, which is again not a desirable attribute for a pharmaceutical or food excipient. PCT Publication WO99/25197A1 discloses a fenugreek seed material having reduced odor and taste. The method of preparing the flaked/ground alcohol extracted fenugreek seed material, comprises the steps of: flaking a fenugreek seed to form a fenugreek preparation, extracting soluble components from the fenugreek preparation by extraction of the fenugreek preparation with an alcohol solvent at a cool extraction temperature to produce fenugreek solid; treating the fenugreek solid to remove the alcohol solvent to produce a dry solid; and grinding the dry solid into a powder to produce the fenugreek seed material. The process disclosed herein results in a product having a high amount of protein (about 20-40%), which not only reduces the amount of dietary fiber content in the end product but is also undesirable as a pharmaceutical and food excipient.
PCT Publication WO01/74371A1 discloses fenugreek mucilages and galactomannans. The fenugreek mucilages discussed herein are in the form of flour with grain size distribution less than 100 μm, consisting of 60 weight % of oses, relative to the composition total weight, namely mannose, galactose, glucose, arabinose, xylose, rhamnose, D-galacturonic acid with 50-55 weight % of doses consisting of galactomannans, and 5 weight % of proteins. The galactomannans disclosed further consist exclusively as doses, of mannose and galactose, with a mannose/galactose ratio of 1, 1.2. The key feature of the invention is pulverization of non-lipid fraction of fenugreek seed at sub-zero temperatures (−195 degrees) to improve the solubility of non-lipid fraction of fenugreek seed in the extracting solvent. This requires a specialized facility to carry out such an operation thereby increasing the cost of isolation of dietary fiber. U.S. Pat. No. 5,847,109 discloses an isolated galactomannan having at least 50 repeating units of mannose and galactose in a ratio of between 0.5-1.0 and 1.8-1.0, and having a protein content of less than 20 wt. %, a saponin content of less than 5 wt. %, and a lipid content of less than 1 wt. %. The process of isolation of galactomannan (soluble fiber) described herein involves use of organic solvents and high temperatures as well as specialized equipment. This process also involves treatment with polar alcohols that tend to reduce the yield of the soluble dietary fiber. The process further involves reduction in protein content by using chromatographic techniques that are difficult and expensive to carry out at commercial scale.
PCT Publication WO 2005/009453A1 discloses a process for the preparation of debitterised and defatted fenugreek powder containing 4-hydroxy isoleucine and rich in soluble dietary fiber. The process described includes extraction of powdered fenugreek seeds with ethanol/methanol to obtain debitterised powder containing 4-hydroxy isoleucine. This debitterised powder on sieving through a mesh size of 50 to 90 BSS yields upper and lower layers, of which upper layer is said to contain more of soluble fiber about 40 to 45%. That the fenugreek seeds are treated in this process with polar alcohols at elevated temperatures for debitterisation, the process may lead to loss of some amount of dietary fibers. Further since the entire seed with the husk and embryo is utilized in this extraction process, the debitterised powder obtained has higher protein content (20-45% by weight) which is an undesirable attribute for a pharmaceutical or food excipient. PCT Publication WO.2009/057125A1 discloses a process for improving the organoleptic property of the dietary fiber obtained from the seeds of fenugreek by debitterisation, deodourisation and decolourisation of the seed. The process disclosed herein consist of the steps of soaking the plant parts overnight in a solvent; powdering plant parts to obtain powder, extracting the powdered plant parts using a solvent; separating the extracted components, precipitating the separated components to obtain gum; and washing precipitated gum followed by drying to obtain organoleptically improved dietary fiber that comprises proteins around 25% and galactomannnans around 75%. Further since the entire seed is utilized in this extraction process, dietary fiber obtained has high protein content which is an undesirable attribute for a pharmaceutical or food excipient.
Thus methods disclosed in the art to isolate dietary fibers and other components from fenugreek seeds are non-specific and involve the use of costly and specialized equipments, organic solvents or energy intensive methods for extraction. Further the isolation of dietary fibers relates particularly to isolation of soluble dietary fibers for their therapeutic use or to isolation of soluble fibers with high protein content for nutritional purposes. Hence though attempts have been made towards isolating dietary fibers primarily soluble fibers, these have not been directed to isolation of dietary fibers from fenugreek having a particular ratio of insoluble to soluble fibers to obtain an excipient that can be used in various pharmaceutical or cosmetic compositions and food, nutritional or dietary preparations. Further various marketed products based on Fenugreek fibers available for health or nutritional purposes also mainly have soluble fibers in their compositions with insoluble dietary fibers if present being present at relatively low amounts. Fenfiber®, for example, manufactured by Emerald Seed Products for blood sugar and cholesterol management as well as for good digestive health, comprises 92% total fiber content with 80% soluble and 12% insoluble fibers i.e., has ratio of insoluble to soluble dietary fibers of 0.15. FenuPure from NatuR&D known to have properties of blocking the adsorption of glucose into blood and binding cholesterol implicated in heart disease has a total fiber content of greater than 85% and soluble fibers of greater than 80%, thereby having a ratio of insoluble to soluble fibers of about 0.07. Thus particularly the art fails to teach isolation of dietary fibers from fenugreek seeds comprising insoluble and soluble dietary fibers in a ratio of 0.2 to 1 and comprising not more than 10 weight % of protein.
EP1697050 discloses solvent free process of obtaining insoluble fiber rich fraction and further a highly purified fiber rich fraction from fenugreek seeds. The fractions obtained have at least 50% of dietary fiber with ratio of insoluble to soluble dietary fiber of greater than 0.8, preferably greater than 1.2 and a protein content of not more than 10 weight %. Though the solvent free process provides dietary fiber fractions with ratio of insoluble to soluble dietary fiber of greater than preferably 1.2, it does not disclose in any manner dietary fiber fractions or processes for obtaining the same wherein the ratio of insoluble to soluble fibers is lesser than 1 and protein content not more than 10 weight % that also exhibits necessary characteristics required of a pharmaceutical or food excipient such as viscosity, swelling index, water holding capacity etc.
Varying ratios of insoluble and soluble fibers and other constituents such as proteins in the extracts derived from fenugreek seeds determine the applicability of the extract as an excipient in pharmaceutical or cosmetic compositions and food, nutritional or dietary preparations. Excipients comprising insoluble and soluble fibers in a ratio of not more than 1 have properties and applications that are different from those comprising insoluble and soluble fibers in a ratio of more than 1. The differences in the chemical constitution and thereby the properties of soluble and insoluble dietary fibers results in differences in the applications of the products comprising them in varied ratios. Additionally in cases where the ratio of insoluble to soluble dietary fibers is less than 1, fiber based products with ratios of insoluble to soluble fibers of less than 0.2 do not possess properties desirable of pharmaceutical excipient. The present inventors after identifying the importance of varied ratio of insoluble to soluble fibers provide an excipient from fenugreek seeds comprising insoluble to soluble dietary fibers in a ratio of less than 1 with protein content of not more than 10 weight % and processes for production thereof. The excipient provided by the inventors of the present invention can be used industrially as a pharmaceutical or food excipient.